diff options
| author | Dae R. Jeong <dae.r.jeong@kaist.ac.kr> | 2020-10-22 04:21:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-12-30 13:25:49 +0300 |
| commit | b85abab5913d89ee78bc5bb08231acb578677898 (patch) | |
| tree | ce0b18bc98659691815c2420d43bf855e0f0fe29 /drivers/md | |
| parent | 268a84d36ee80752e73db4a3010cac42c7dbdc2b (diff) | |
| download | linux-b85abab5913d89ee78bc5bb08231acb578677898.tar.xz | |
md: fix a warning caused by a race between concurrent md_ioctl()s
commit c731b84b51bf7fe83448bea8f56a6d55006b0615 upstream.
Syzkaller reports a warning as belows.
WARNING: CPU: 0 PID: 9647 at drivers/md/md.c:7169
...
Call Trace:
...
RIP: 0010:md_ioctl+0x4017/0x5980 drivers/md/md.c:7169
RSP: 0018:ffff888096027950 EFLAGS: 00010293
RAX: ffff88809322c380 RBX: 0000000000000932 RCX: ffffffff84e266f2
RDX: 0000000000000000 RSI: ffffffff84e299f7 RDI: 0000000000000007
RBP: ffff888096027bc0 R08: ffff88809322c380 R09: ffffed101341a482
R10: ffff888096027940 R11: ffff88809a0d240f R12: 0000000000000932
R13: ffff8880a2c14100 R14: ffff88809a0d2268 R15: ffff88809a0d2408
__blkdev_driver_ioctl block/ioctl.c:304 [inline]
blkdev_ioctl+0xece/0x1c10 block/ioctl.c:606
block_ioctl+0xee/0x130 fs/block_dev.c:1930
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
This is caused by a race between two concurrenct md_ioctl()s closing
the array.
CPU1 (md_ioctl()) CPU2 (md_ioctl())
------ ------
set_bit(MD_CLOSING, &mddev->flags);
did_set_md_closing = true;
WARN_ON_ONCE(test_bit(MD_CLOSING,
&mddev->flags));
if(did_set_md_closing)
clear_bit(MD_CLOSING, &mddev->flags);
Fix the warning by returning immediately if the MD_CLOSING bit is set
in &mddev->flags which indicates that the array is being closed.
Fixes: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop")
Reported-by: syzbot+1e46a0864c1a6e9bd3d8@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Dae R. Jeong <dae.r.jeong@kaist.ac.kr>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/md.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index a4e7e6c025d9..70edcb27e7d3 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7214,8 +7214,11 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, err = -EBUSY; goto out; } - WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); - set_bit(MD_CLOSING, &mddev->flags); + if (test_and_set_bit(MD_CLOSING, &mddev->flags)) { + mutex_unlock(&mddev->open_mutex); + err = -EBUSY; + goto out; + } did_set_md_closing = true; mutex_unlock(&mddev->open_mutex); sync_blockdev(bdev); |